By Robert Herriman  @bactiman63

As 2019 comes to a close, the number of big, important infectious disease news and outbreak was in no shortage since January.

So, it becomes my annual task to try to take it all, sort it out, and create a Top 10 list. This is what I came up with this year:

10. Eastern Equine Encephalitis (EEE) in the US


After reporting an average of seven human EEE cases annually in the United States over the past decade, 2019 saw a particularly robust and deadly year.

This year, there were 38 confirmed cases of human EEE disease, including 15 deaths. While 10 states reported human cases, Massachusetts (12) and Michigan (10) were hit hardest.

What to expect in 2020? Time will tell.

9. Global malaria

While we don’t have the complete picture for malaria globally in 2019, in December, the World Health Organization released the World malaria report 2019.

What we find in the report is some great news for South Asia. Six countries across the Mekong River basin — Cambodia, China, Laos, Myanmar, Thailand and Vietnam–saw malaria cases drop by 76 percent and malaria-related deaths fell by 95 percent.

However, African countries did report an increase of 1 million cases from 2017 to 2018, and the continent accounted for almost 94 percent of global cases and deaths from the disease in 2018.

8. Lassa fever

Lassa fever remains a major public health challenge in West Africa with Nigeria bearing the highest burden.

Through the first 11 months of the year, Nigeria reported some 800 confirmed cases and 166 deaths for a CFR of greater than 20 percent.

In addition to Nigeria, Liberia and Sierra Leone have reported outbreaks of the viral disease, albeit much smaller. Imported Lassa fever was also reported in a resident of the Netherlands that was working in Sierra Leone.

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7. Vaccines

Vaccines in the news were often in 2019–for both good and bad reasons. The antivaxxer movement has shown the public health problems they caused in such diverse areas of the globe as New York City and Samoa.

On the positive side, vaccine research has brought us an Ebola vaccine, and promising work on vaccines for a universal flu vaccine, Lassa fever, EEE and chikungunya vaccines, to name a few.

6. African Swine fever in Asia

While African swine fever (ASF) was first reported in Asia in China in Aug. 2018, 2019 saw the expansion of the animal disease on the continent.

Vietnam, the Philippines, South and North Korea, Myanmar, Laos, Cambodia, Timor-Leste and most recently, Indonesia, reported outbreaks in 2019 resulting in millions of pigs getting culled.

5. Hepatitis A in the United States

The first hepatitis A outbreaks began in 2016 with 2 states and have grown to 30 states and some 30,000 cases in 2019.

Thousands of cases were reported again this year. While Kentucky has seen a cumulative 5,000 cases since 2017, the numbers have slowed in 2019.

However, in Florida, more than 3,300 hepatitis A outbreak cases have been reported.

4. The polio resurgence

In what is arguably the most disappointing infectious disease story of 2019, polio has seen an unfortunate resurgence this year.

In 2018, 33 total wild poliovirus 1 (WPV1) were reported (only 12 in Pakistan). Official data from the Global Polio Eradication Initiative shows 125 total cases year-to-date, with over 100 in Pakistan.

Media reports put the Pakistan case count even higher at 119.

In addition to the WPV cases reported, the number of circulating vaccine-derived poliovirus has risen significantly this year–241 cases this year ( in 16 African and Asian countries) compared to 104 in 2018.

The twenty-third meeting of the Emergency Committee under the International Health Regulations (2005) (IHR) regarding the international spread of poliovirus was convened by the Director General earlier this month and it was noted they were “gravely concerned” by the significant increase in WPV1 cases globally and said the rapid emergence of multiple cVDPV2 strains in several countries is unprecedented and very concerning, and not yet fully understood.

There was some great news concerning polio in 2019–over the summer,  the three year anniversary of no WPV1 cases reported in Nigeria occurred.

In addition, wild poliovirus type 3 was declared eradicated in 2019.

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3. Ebola outbreak in the Democratic Republic of the Congo (DRC)

Last year’s number one story comes in at number 3 in 2019. The 10th Ebola Virus Disease (EVD) outbreak in the DRC was declared in August 2018 and the outbreak continues on through the end of 2019.

To date, 3,373 confirmed and probable cases have been reported (the 2nd largest EVD outbreak in history), including 2,231 deaths.

Médecins Sans Frontières (MSF) said this week–While there are positive signs that the number of cases is slowly reducing, the outbreak remains a serious public health concern, and it is unclear when it may end.

We also got a serious scare over the summer when Uganda announced that three people had been positively diagnosed with Ebola, the first cross-border cases since the outbreak began. An additional case was reported soon after in late August.

The work of health workers in North Kivu and surrounding areas have been hampered by armed groups and other forms of violence.

2. Global Dengue fever

The numbers are staggering in many parts of the world–3 million dengue cases in Latin America in 2019, a new record, with Brazil reporting more than 2 million cases alone.

The Philippines has reported more than 400,000 cases, almost double the cases reported in 2018.

Bangladesh saw more than 100,000 cases in 2019, many more cases than were reported in the country from 2000-2018.

That’s just a short list.

1. Global measles

Again, I could just list the numbers:~300,000 and more than 5,000 deaths in the DRC, ~250,000 in Madagascar (since September 2018), ~60,000 in Ukraine, ~55,000 in Nigeria and ~45,000 in the Philippines– and again, this is just the short list.

In the United States, nearly 1,300 measles cases were reported in 2019, the greatest number of cases reported since 1992.

While the global totals for measles in 2019 will not be released for some time; however, with more than 140,000 measles-related fatalities seen in 2018, I could only imagine what will be reported.

Well, there you have it–this is the list I’ve complied after following infectious diseases and outbreaks closely over the course of the year.

Check out some previous “end-of-year” lists I published:

10 Most Important Infectious Disease Stories of 2018: Outbreak News Today

10 Most Important Infectious Disease Stories of 2017: Outbreak News Today

The Top 10 Infectious Disease News stories of 2014 on Outbreak News Today

The Top 10 Infectious Disease and Outbreak News stories of 2013


The Top 10 Biggest Vaccine Stories Of 2016

Top 10 Deadliest Viruses